need help reinstalling lower unit (GEARCASE)

[college_guy]

i am having a hard time reinstalling my lower unit.. its about an inch away from going in. ive put it in forward, neutral, but not reverse. my motor is a 72 850 merc. ive tried putting it in while turning the flywhell clockwise.. i dont know if its the shift shaft that arent aligning or what. i hear that you can move the gearcase into gear or something.. HOW would you get to the gearcase and where would i find it.. im having trouble.. i dont want to bring it to the shop as well.. any help would be greatly appriciated.

 

[arsenalpsu]

Re: need help reinstalling lower unit (GEARCASE)

It's mostly likely your shifting rod that's not lining up. When i installed mine on my 115hp i put shifter and LU in neutral. Once it's an inch from going in i move the throttle just about an inch or 2 and it slides right in. Then you have to make sure you didn't move it to far that it won't shift right. It's hard if you're the only one doing it. Have a friend slowly move your throttle into forward as you push the LU, when it lines up it should slide up.

 

[Chris1956]

Re: need help reinstalling lower unit (GEARCASE)

To add to what the otherposter said. Use neutral for the control and gearcase. The propshaft will spin both ways freely, when gearcase is in neutral.

There is a plastic fitting around the shift rod. Make sure that piece is in the midsection, as it will hold the upper shift rod in the correct position. Turn the flywheel by hand while installing the gearcase, so the spline on the driveshaft will align with the crankshaft.

 

[Texasmark]

Re: need help reinstalling lower unit (GEARCASE)

My Merc service manual says to have everything in F gear. However the last time I changed an impeller, I did as you have beed directed using N and rotating the engine by hand and that was before I got this manual.

In thinking about the manual's method, you are working on the lower unit possibly alone (I do all my work alone). Putting everything in F allows you to use the prop (it's right there handy) to turn the driveshaft for alignment with the powerhead. The other thing it does is help to insure that the lower unit and the shift levers and controls are all in alignment so that once back together you can access all 3 gears with the control in the correct position.

BUTTTTTTTTTTT do what works for you. Grin.

Mark

 

[Chris1956]

Re: need help reinstalling lower unit (GEARCASE)

Mark, The advantage to using neutral is that it ony has one position, so the alignment is either good or bad. Forward and Reverse have a range, so the shift alignment can be one spline off and partially work. Also, removal of the prop makes the LU lighter, especially if it is a SS prop. Turning the flywheel by hand to line up the driveshaft splines is easy.

For my money, neutral is the way to go on outboards. Of course Alpha I drives require you to use forward, or the shift cradle won't disengage.

 

[college_guy]

Re: need help reinstalling lower unit (GEARCASE)

my old lower unit had a pin at the top but my new one i just bought doesnt have the pin at the top of the drive shiift.. would that make a difference and do i need a lower unit with the pin at the top?? as for my lower unit ill try to resemble.. i have the manual but thats no help. I think my problem is not aligning the both shafts at the same time is that the reason why its probably not lining up? ill most like use neutral ill try it later and letcha guys know.. thanks for the input...god bless

 

[Chris1956]

Re: need help reinstalling lower unit (GEARCASE)

Some Lower units have the reload pin, and need it. Some do not, because they do not need it.

 

[sschefer]

Re: need help reinstalling lower unit (GEARCASE)

Putting both the shift lever and the lower unit shift shaft in the forward gear position is not only the correct method but also the easiest. If you use neutral and the drive shaft is up against the crankshaft both will turn when you rotate the flywheel and only dumb luck will get it lined up on the first try.

If you use forward, the resistance of the gearcase is enough to cause the drive shaft to slip when rotating the flywheel and allow it to align almost instantly.

After a couple of times you'll learn the tricks and that you can use neutral as efficiently as forward. I pull the plug wires and use a remote starter switch to bump the motor and install them with very little effort.

There was a lot of cussing along the road to success, I think most of us will admit that!

 

[Moody Blue]

Re: need help reinstalling lower unit (GEARCASE)

I've got to agree with Chris1956 on this one. The lower unit shift shaft, in both forward and reverse, has alot of free-play. It is easy to get the upper and lower splined shafts out of alignment by one notch possibly causing incomplete shifting when reassembled.

In neutral, both the lower unit and control box have detent stops where the engagement is absolute. No guessing.

I've run into this situation on my motor last summer.

 

[arsenalpsu]

Re: need help reinstalling lower unit (GEARCASE)

LOL I can relate to sschefer in regards to the swearing and what not. The first time you do this it is a pain in the @ss- BUT once you do get her to go in, it gets easier. (insert sexual joke here) Just take your time and don't get mad.

 

[college_guy]

Re: need help reinstalling lower unit (GEARCASE)

should it just slide in easily or do you have to put the nuts in a bit, align the shafts and tighten it up? i have enough space to put the bolts on BUT i does not go in fully... i can test to see if it does go in the shafts by shifting the gears.. the question is should it slide in easily or do you have to force it in with the bolts?

 

[Chris1956]

Re: need help reinstalling lower unit (GEARCASE)

You need to wiggle it into place, after you line up the driveshaft and shiftshaft. You may use the nuts to hold it in place. Use fingers only to tighten them. If you force it you will ruin the crankshaft or driveshaft splines.